A variety of telecommunication systems utilize traditional telephone company local subscriber loops to carry high rate digital transmissions. Examples include a variety of digital subscriber loop (DSL) services, such as high-rate DSL (HDSL), asymmetric DSL (ADSL), very high-rate DSL (VDSL) and others. The varieties of DSL service will be referred to herein generally as xDSL.
The xDSL services share the same carrier with traditional analog telephony, commonly referred to as plain old telephone service (POTS). To share the same carrier, some sort of multiplexing is used. Typically, this involves frequency division multiplexing (FDM). POTS typically occupies the frequencies of between 300 and 3400 Hz while the xDSL service typically occupies some band of frequencies above the POTS service.
To isolate the POTS service from the xDSL transceiver, a splitter, or POTS splitter, is used. These splitters generally have a low-pass filter to permit passing of the POTS service and a high-pass filter to permit passing of the xDSL service. To provide maximum possible transfer of power of a signal between a source and its load, the POTS splitter must have its impedance matched to the transmission line or carrier.
For the reasons stated above, and for other reasons stated below that will become apparent to those skilled in the art upon reading and understanding the present specification, there is a need in the art for alternative apparatus and methods to facilitate line impedance matching in a POTS splitter.